This invention relates generally to a process for preparing a product from a plurality of ingredients by combining the ingredients to form a multiple weight batch thereof, and then taking individual weight batches from the multiple batch; more particularly, the invention relates to a control for accurately determining the weight of the combination of ingredients in an individual batch taken from the multiple batch and correcting the weight of subsequent batches for any weight error in an individual batch.
In the formation of certain products such as soaps, food mixes, or bakery products, selected quantities of different ingredients are combined and mixed (blended) together to form the product. In large scale industrial applications of preparation of such products, multiple weight batches are prepared at one time. Accordingly, the quantities of the different ingredients making up a product are significantly larger than one batch of the product, but are in the same proper relative proportions. The larger multiple weight batch of combined ingredients for a particular product is then divided into individual batches of the desired end-product size which are uniform in nature. The principal advantages to preparing the larger multiple weight batch of combined ingredients, is that the bulk weights of the individual ingredients that make up the product can be used as received and the blending of the ingredients can be more accurately controlled for uniformity of the product. For example, the measuring of any particular ingredient need only be done once; and the larger the quantity of product being measured, the more accurate the measurement can be made. However, any measuring error in the larger multiple batch of combined ingredients has an adverse effect on the overall economy of the process in that the last of the individual batches formed from the larger batch absorbs the entire error (last individual batch will be under or over size depending upon whether the measuring error was less or more than the desired quantity) and if the error is too large that batch must be thrown out.
Recently, multiple batch product preparation techniques have been developed using sophisticated controls, such as computers, to assist in measuring of individual ingredients and compensating for measuring errors. Typically, error compensation is accomplished by continuously monitoring the flow rate or weight of the individual constituent ingredients and accordingly adjusting the processing cycle. The adjustment can be made continuously for a flow rate monitored process or periodically for a weight monitored processes. In either instance adjustment is made in the batch being processed or the next subsequent processed batch. This tends to generate an immediate overcompensation in the next processed batch, or a progressive carry-over error which accumulates such that at least the last batch is again out of normal tolerance limits and is unusable.